Ionization latch indicator and housing receptacle therefor



March 17, 1910 J. E. BIGHAM ETAL 3,501,666

IONIZATION, LATCH INDICATOR AND HOUSING RECEPTACLE THEREFOR Filed March14, 1967 INVENTORS J. E. B! GHA M BY H. E. CRIDER United States Patent3,501,666 IONIZATION LATCH INDICATOR AND HOUSING RECEPTACLE THEREFORJames E. Bigham, Greenwood, S.C., and Harold E. Crider, Pensacola, Fla.,assignors to Monsanto Company, St. Louis, M0., a corporation of DelawareFiled Mar. 14, 1967, Ser. No. 623,050 Int. Cl. H01j 17/34 US. Cl.313-210 1 Claim ABSTRACT OF THE DISCLOSURE The present invention relatesto a circuit element for energizing a load during a time interval longerthan the duration of an initiating signal, and more particularly to suchan element additionally capable of functioning as an annunciator orindicator.

Conventional prior art elements for performing these functions include arelay with holding contacts, and a thyratron tube. Each of these priorart devices is bulky and expensive. According to the present invention asmall chamber of an ionizable gas is arranged with suitable exteriorcontacts and structure so as to be capable of performing both functions,at a considerable savings in cost and complexity.

The primary object of the invention is to provide a novel circuitelement for maintaining current flow for a time interval longer thanthat of an initiating signal.

A further object is to provide a circuit element of the above characterwhich functions as an annunciator.

Other objects of the invention will in part be obvious and will in partappear hereinafter.

For a more complete understanding of the nature and objects of theinvention, reference should be had to the following detailed descriptiontaken in connection with the accompanying drawings, in which:

FIGURE 1 is a schematic vertical sectional view of a first embodiment ofthe invention, and

FIGURE 2 is a similar schematic vertical sectional view of a secondembodiment of the invention.

Referring now to FIGURE 1, the circuit element according to the presentinvention includes a base member 20 defining a cylindrical bore 22having an open upper end. An insulating chamber 24, filled with anionizable gas such as neon, is slideably mounted in bore 22. Preferablychamber 24 is formed of glass or other light-permeable material. A firstelectrode 26 is mounted within chamber 24 and is supported by terminal28 extending through lower wall 30 of chamber 24. The lower external endof terminal 28 is offset to form the movable contact of a normallyclosed switch. Fixed contact 32 of the normally closed switch has oneend offset and interposed between the lower end of terminal 28 andchamber 24, and extends through the bottom wall 34 of base 20. A secondelectrode 36 within chamber 24 is connected through bottom wall 30 to aresilient spring member 38 interposed between walls 30 and 34. A secondspring 40 is likewise 3,501,666 Patented Mar. 17, 1970 "ice interposedbetween walls 30 and 34, and is connected to terminal 42 within chamber24. An electrical resistance heating wire 44 connects electrode 36 andterminal 42.

Chamber 24 and movable contact 28 are therefore resiliently urged bysprings 38 and 40 upwardly toward the open end of bore 22, urgingmovable contact 28 into engagement with fixed contact 32. A low voltagesource 46 is connected between first contact 32 and spring 38, while ahigh voltage source 48 is connected between spring 38 and spring 40 by aseries switch 50.

When chamber 24 is filled with a suitable ionizable gas, such as neon,argon, or the like, ionization of the gas may be initiated bymomentarily closing switch 50, thus energizing heater 44. The voltagesupplied by source 46 should be below the threshold or ionizationpotential of the gas in chamber 24, at the particular gas pressure andelectrode spacirig employed, but should be higher than the holdingpotential (the potential required to maintain conduction through the gasonce conduction is attained through other means). Once conduction hasbeen initiated between electrodes 26 and 36, it will be maintained untilthe normally closed switch (formed by elements 28 and 32) is opened.This may be accomplished by manually pressing chamber 24 into bore 22,temporarily interrupting contact between elements 28 and 32.

FIGURE 2 illustrates a variation wherein the ionizable gas is confinedin a separate glow tube 52 mounted inside chamber 24. Energization ofheater 44 from source 48 initiates conduction through tube 52, whichcontinues until current flow is interrupted by depressing chamber 24.

Having described our invention what we claim as new and desire to secureby Letters Patent is:

1. An ionization latch, comprising in combination:

(a) a housing defining a cylindrical bore having an open end,

(b) an insulating chamber filled with an inert gas, said chamber beingslidably mounted in said bore, at least the portion of said insulatingchamber nearest said open end being formed of a light-permeablematerial,

(0) a first electrode in said chamber connected to an external contactmovable with said chamber,

(d) a fixed contact mounted in said housing adjacent said externalcontact and interposed between said external contact and said open end,

(e) means resiliently urging said chamber and said external contacttoward said open end whereby said external contact is normally urgedinto engagement with said fixed contact,

(f) a further electrode in said chamber,

(g) means for applying to said fixed contact and to said furtherelectrode a voltage higher than the holding potential and less than theionizing potential between said electrodes,

(h) and means for initiating discharge between said electrodes.

References Cited UNITED STATES PATENTS 2,832,912 4/1968 Lake 313-210 XJAMES W. LAWRENCE, Primary Examiner P. C. DEMEO, Assistant Examiner US.Cl. X.R.

